Social deficits in mice prenatally exposed to valproic acid are intergenerationally inherited and rescued by social enrichment.

Intergenerational transmission of the effects of environmental factors on brain function and behavior can occur through epigenetic mechanisms. Valproic acid (VPA) is an anticonvulsant drug that, when administered during pregnancy, causes various birth defects. The mechanisms of action are largely unclear: VPA can reduce neuronal excitability, but it also inhibits the histone deacetylases, affecting gene expression. Here we evaluated whether the effects of valproic acid prenatal exposure on autism spectrum disorder (ASD)-related behavioral phenotypes can be transmitted to the second generation (F2) through the paternal or the maternal lineage. Indeed, we found that F2 males of the VPA pedigree show reduced sociability, which can be rescued by exposing the animals to social enrichment. Moreover, as is the case for F1 males, F2 VPA males show increased c-Fos expression in the piriform cortex. However, F3 males show normal sociability, indicating that VPA's effects on this behavior are not transgenerationally inherited. Female behavior is not affected by VPA exposure, and we found no evidence of maternal transmission of the consequences of this pharmacological treatment. Finally, all animals exposed to VPA and their descendants show reduced body weight, highlighting an intriguing effect of this compound on metabolism. We propose the VPA model of ASD as a valuable mouse model to study the role of epigenetic inheritance and its underlying mechanisms affecting behavior and neuronal function.

Juvenile handling rescues autism-related effects of prenatal exposure to valproic acid.

Environmental factors acting on young animals affect neurodevelopmental trajectories and impact adult brain function and behavior. Psychiatric disorders may be caused or worsen by environmental factors, but early interventions can improve performance. Understanding the possible mechanisms acting upon the developing brain could help identify etiological factors of psychiatric disorders and enable advancement of effective therapies. Research has focused on the long-lasting effects of environmental factors acting during the perinatal period, therefore little is known about the impact of these factors at later ages when neurodevelopmental pathologies such as autism spectrum disorder (ASD) are usually diagnosed. Here we show that handling mice during the juvenile period can rescue a range of behavioral and cellular effects of prenatal valproic acid (VPA) exposure. VPA-exposed animals show reduced sociability and increased repetitive behaviors, along with other autism-related endophenotypes such as increased immobility in the forced swim test and increased neuronal activity in the piriform cortex (Pir). Our results demonstrate that briefly handling mice every other day between postnatal days 22 and 34 can largely rescue these phenotypes. This effect can also be observed when animals are analyzed across tests using an "autism" factor, which also discriminates between animals with high and low Pir neuron activity. Thus, we identified a juvenile developmental window when environmental factors can determine adult autism-related behavior. In addition, our results have broader implications on behavioral neuroscience, as they highlight the importance of adequate experimental design and control of behavioral experiments involving treating or testing young animals.

Early estradiol exposure masculinizes disease-relevant behaviors in female mice.

Most psychiatric disorders show a sex bias in incidence, symptomatology, and/or response to treatment. Males are more susceptible to neurodevelopmental disorders including autism spectrum disorder and attention-deficit activity disorder, while women are more prone to major depressive disorder and anxiety disorders after puberty. A striking difference between males and females in humans and other mammals is that males undergo a process of brain masculinization due to the early exposure to gonadal hormones. In rodents, this developmental organization of the brain is essential for adult males to express the appropriate sexual behaviors in the presence of a receptive female. Our goal was to determine whether this process of brain masculinization influences behaviors relevant to psychiatric disorders. To this aim, we studied sex differences and the effect of neonatal 17ß-estradiol benzoate treatment of female mice on different disease-relevant behaviors. Our analysis includes postnatal behavior, juvenile play, and adult tests for sociability, repetitive behaviors, anxiety, and depression. Our results show that the sex differences observed in exploration, repetitive behaviors, and depression-related behaviors are largely reduced when females are neonatally treated with 17ß-estradiol benzoate. These results suggest a role of neonatal sex steroids in the development of disease-relevant behaviors and provide evidence supporting a role for perinatal exposure to estrogens and androgens on the development and manifestation of psychiatric disorders.

Sex-specific effects of prenatal valproic acid exposure on sociability and neuroinflammation: Relevance for susceptibility and resilience in autism.

Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders with an incidence four times higher in boys than in girls. By analyzing the effect of sex in a mouse model of ASD, we were able to identify immune alterations that could underlie this sex bias. Pregnant mice were injected subcutaneously with 600 mg/kg of valproic acid (VPA) or saline at gestational day 12.5. Their male and female offspring were evaluated in a social interaction test at adulthood, and only male VPA mice showed reduced sociability levels and a lack of preference for the social stimulus over a novel object. We then analyzed the corticosterone (CORT) response to an inflammatory stimulus, as a measure of the hypothalamus-pituitary-adrenal (HPA) function, and the neuroinflammatory state in adult and young animals. Adult VPA males exhibited increased basal CORT levels, while VPA females showed levels comparable to controls. As male mice showed a blunted CORT response at PD21 when compared to female mice, we propose that this early dimorphism could explain the different effects of VPA on HPA function. In addition, prenatal VPA exposure resulted in altered astroglial and microglial cell density levels in the cerebellum and dentate gyrus of adult mice. These neuroinflammatory effects were more pronounced in females than males, and appeared at early developmental stages. Hence, these postnatal glial density differences could underlie the behavioral alterations observed in adulthood, when only males show a social deficit. Our work contributes to the understanding of biological mechanisms affected by VPA on male and female rodents and shed light on the study of possible resilience mechanisms in the female population and/or susceptibility to ASD in boys.

Sociability deficits after prenatal exposure to valproic acid are rescued by early social enrichment.

Background: Autism spectrum disorder (ASD) is characterized by impaired social interactions and repetitive patterns of behavior. Symptoms appear in early life and persist throughout adulthood. Early social stimulation can help reverse some of the symptoms, but the biological mechanisms of these therapies are unknown. By analyzing the effects of early social stimulation on ASD-related behavior in the mouse, we aimed to identify brain structures that contribute to these behaviors. Methods: We injected pregnant mice with 600-mg/kg valproic acid (VPA) or saline (SAL) at gestational day 12.5 and evaluated the effect of weaning their offspring in cages containing only VPA animals, only SAL animals, or mixed. We analyzed juvenile play at PD21 and performed a battery of behavioral tests in adulthood. We then used preclinical PET imaging for an unbiased analysis of the whole brain of these mice and studied the function of the piriform cortex by c-Fos immunoreactivity and HPLC. Results: Compared to control animals, VPA-exposed animals play less as juveniles and exhibit a lower frequency of social interaction in adulthood when reared with other VPA mice. In addition, these animals were less likely to investigate social odors in the habituation/dishabituation olfactory test. However, when VPA animals were weaned with control animals, these behavioral alterations were not observed. Interestingly, repetitive behaviors and depression-related behaviors were not affected by social enrichment. We also found that VPA animals present high levels of glucose metabolism bilaterally in the piriform cortex (Pir), a region known to be involved in social behaviors. Moreover, we found alterations in the somatosensory, motor, and insular cortices. Remarkably, these effects were mostly reversed after social stimulation. To evaluate if changes in glucose metabolism in the Pir correlated with changes in neuronal activity, we measured c-Fos immunoreactivity in the Pir and found it increased in animals prenatally exposed to VPA. We further found increased dopamine turnover in the Pir. Both alterations were largely reversed by social enrichment. Conclusions: We show that early social enrichment can specifically rescue social deficits in a mouse model of ASD. Our results identified the Pir as a structure affected by VPA-exposure and social enrichment, suggesting that it could be a key component of the social brain circuitry.

Perinatal inflammation and adult psychopathology: From preclinical models to humans.

Perinatal environment plays a crucial role in brain development and determines its function through life. Epidemiological studies and clinical reports link perinatal exposure to infection and/or immune activation to various psychiatric disorders. In addition, accumulating evidence from animal models shows that perinatal inflammation can affect various behaviors relevant to psychiatric disorders such as schizophrenia, autism, anxiety and depression. Remarkably, the effects on behavior and brain function do not always depend on the type of inflammatory stimulus or the perinatal age targeted, so diverse inflammatory events can have similar consequences on the brain. Moreover, other perinatal environmental factors that affect behavior (e.g. diet and stress) also elicit inflammatory responses. Understanding the interplay between perinatal environment and inflammation on brain development is required to identify the mechanisms through which perinatal inflammation affect brain function in the adult animal. Evidence for the role of the peripheral immune system and glia on perinatal programming of behavior is discussed in this review, along with recent evidence for the role of epigenetic mechanisms affecting gene expression in the brain.

Postnatal behavioral and inflammatory alterations in female pups prenatally exposed to valproic acid.

In Autism Spectrum Disorders (ASD), a bias to a higher incidence in boys than in girls has been reported. With the aim to identify biological mechanisms acting in female animals that could underlie this bias, we used an extensively validated mouse model of ASD: the prenatal exposure to valproic acid (VPA). We found postnatal behavioral alterations in female VPA pups: a longer latency in righting reflex at postnatal day (P) 3, and a delay in the acquisition of the acoustic startle response. We also analyzed the density of glial cells in the prefrontal cortex, hippocampus and cerebellum, in VPA and control animals. Female VPA pups showed alterations in the density of astrocytes and microglial cells between P21 and P42, with specific dynamics in each brain region. We also found a decrease in histone 3 acetylation in the cerebellum of female VPA pups at P14, suggesting that the changes in glial cell density could be due to alterations in the epigenetic developmental program. Finally, no differences in maternal behavior were found. Our results show that female VPA pups exhibit behavioral and inflammatory alterations postnatally, although they have been reported to have normal levels of sociability in adulthood. With our work, we contribute to the understanding of biological mechanisms underlying different effects of VPA on male and female rodents, and we hope to help elucidate whether there are factors increasing susceptibility to ASD in boys and/or resilience in girls.

Ciencia y ficción en la utilización terapéutica de las células madres / Science and fiction in the therapeutic use of stem cells

En los últimos años ha surgido un fuerte interés en las investigaciones que apuntan a utilizar células madres como fuente de distintos tipos celulares, tejidos y órganos para terapias de reemplazo en distintas enfermedades. Se han identificado distintas fuentes de células madrtes o pñuripotentes, como la médula ósea, la sangre de cordón umbilical, y el embrión. Recientemente se ha demostrado que es posbile reprogramar células adultas de la piel de manera que tengan un potencial similar a las células embrionarias. Sin embargo, a la fecha, sólo se utilizan células de méducla ósea o de sangre de cordón umbilical en el tratamiento de enfermedades hematológicas, y cualquier otro tratamiento se encuentra aún en experimentación. Cada tipo de células madres tiene potencialidades y limitaciones técnicas, que son acompañadas por distintos grados de objeciones éticas. Este trabajo tiene como objetivo describir los tipos de células madres más estudiados hay en día y discutir cuáles son sus fortalezas y sus limitaciones...

Altered peripheral and central inflammatory responses in a mouse model of autism.

Increasing clinical and experimental evidence links immune and inflammatory alterations with the pathogenesis of autism spectrum disorders (ASD). Autistic individuals show signs of neuroinflammation, altered inflammatory responses, and immune abnormalities throughout life. Mice injected subcutaneously with 600 mg/kg valproic acid (VPA600) at gestational day 12.5 show reduced social interaction in adulthood (at 8 weeks of age), and they have been proposed as a mouse model of autism. Here, we show that these adult animals present signs of chronic glial activation in the hippocampus and the cerebellum. Moreover, when they are challenged with a peripheral inflammatory stimulus (intraperitoneal lipopolysaccharides, LPS), VPA600 animals show an exacerbated inflammatory response. Two hours after LPS injection, VPA600 animals secrete more corticosterone to the blood than control mice, and show an increase in the levels of expression of proinflammatory cytokines in the spleen. After LPS challenge, VPA600 mice also show signs of increased neuroinflammation compared with control mice: they have more microglial cells in the hippocampus, and they show higher levels of proinflammatory cytokines in the cerebellum. Our results provide evidence of basal neuroinflammation and an altered inflammatory response in the VPA model of autism. We propose that this model can be used to evaluate the contribution of inflammatory reactivity to autism-related behaviors. These studies will contribute to elucidate the role of the inflammatory alterations observed in ASD individuals.

Bancos de sangre de cordón umbilical / Umbilical cord blood banks

La problemática de los bancos de sangre de cordón umbilical, y en particular, la colecta de sangre del cordón umbilical plantea una serie de cuestiones científicas, médicas, éticas y de salud pública. En la Argentina existe un desconocimiento generalizado sobre qué es dicha colecta, para qué se puede realizar, y qué resultados se esperan de ella. Se relata un caso, elaborado a partir de experiencias reales, cuyo objetivo es que el lector se acerque a la problemática desde una situación concreta

Bancos de sangre de cordón umbilical / Umbilical cord blood banks

La problemática de los bancos de sangre de cordón umbilical, y en particular, la colecta de sangre del cordón umbilical plantea una serie de cuestiones científicas, médicas, éticas y de salud pública. En la Argentina existe un desconocimiento generalizado sobre qué es dicha colecta, para qué se puede realizar, y qué resultados se esperan de ella. Se relata un caso, elaborado a partir de experiencias reales, cuyo objetivo es que el lector se acerque a la problemática desde una situación concreta

Peripheral and central inflammation in autism spectrum disorders.

Recent reports have given a central role to environmental factors in the etiology of autism spectrum disorders (ASD). However, most proposed perinatal factors seem to converge into the activation of the immune system, suggesting that an early inflammatory response could be a unifying factor in the etiology ASD. Here I review the evidence of early immune activation in individuals with ASD, and the chronic peripheral and central alterations observed in the inflammatory response in ASD. This evidence shows that ASD is associated with altered neuroinflammatory processes and abnormal immune responses in adulthood. How these immune alterations can affect developmental programming of adult behavior or directly affect behavior later in life is discussed in the context of both clinical and animal models of research. Recent studies in rodents clearly support a role of elevated cytokines in the behavioral symptoms of ASD, both during development and in adulthood. This article is part of a Special Issue entitled 'Neuroinflammation in neurodegeneration and neurodysfunction'.

Early and adult hippocampal TGF-ß1 overexpression have opposite effects on behavior.

TGF-ß1 is an anti-inflammatory cytokine that is augmented in the brain of autistic patients and that can affect brain development. In this work, we studied the effects of overexpressing TGF-ß1 in the dentate gyrus of adult or young mice on behavior. TGF-ß1 overexpression during postnatal development led to a long-term decrease in social interaction and to long-term increases in self-grooming and depression-related behaviors. Our analysis shows that these behavioral changes correlate with the long-term downregulation of TGF-ß1 and IL-6 expression in the dentate gyrus, as well as to decreases in the mRNA levels of the synaptic protein neuroligin 3 and in the number of Reelin-positive neurons in the dentate gyrus. In contrast, chronic expression of TGF-ß1 during adulthood led to transient opposite effects on these behaviors. These results show a central role of hippocampal TGF-ß1 in the programming and modulation of social interaction, repetitive behavior and depression-related behavior. Finally, our data suggest a role of hippocampal TGF-ß1 and early-life neuroinflammation in the development of the behavioral alterations observed in autism spectrum disorders.

Evaluating the interaction between early postnatal inflammation and maternal care in the programming of adult anxiety and depression-related behaviors.

The perinatal development of the nervous system is influenced by different external and internal stimuli. Previous data show that maternal care and perinatal inflammation can induce long-term changes in anxiety- and depression-related behavior. Our hypothesis is that both maternal care and perinatal inflammation act through interacting biological pathways to program adult behavior. To evaluate this interaction, we combined a protocol of maternal care variation in mice (C57BL/6J x BALB/c reciprocal F1 offspring) with the administration of bacterial wall lipopolysaccharide (LPS) at a previously reported sensitive development age (postnatal day 3, P3). The analysis of maternal behavior revealed that pups from C57BL/6J dams received more maternal attention than those taken care by BALB/c dams. Pups receiving LPS at P3 showed an acute corticosterone response, and a dose-dependent desensitization of this hormonal response when challenged with LPS at adulthood. We analyzed adult behavior on 6 highly validated tests and found an interaction between maternal care and early postnatal LPS on 7 anxiety-related behaviors in 4 different tests. In particular, early postnatal LPS treatment resulted in higher anxiety-related behavior when administered to females receiving more maternal care (C57 pedigree), but reduced depression-related behavior in males of the same pedigree. These results suggest that specific coping strategies are sensitive to maternal care and/or postnatal inflammation programming of adult anxiety- and depression-related behaviors, suggesting that both divergent and convergent mechanisms participate in this programming.

GABA homeostasis contributes to the developmental programming of anxiety-related behavior.

During development, when inhibitory and excitatory synapses are formed and refined, homeostatic mechanisms act to adjust inhibitory input in order to maintain neural activity within a normal range. As the brain matures, synaptogenesis slows and a relatively stable level of inhibition is achieved. Deficits in inhibitory neurotransmission are associated with increased anxiety-related behavior and drugs that potentiate GABA function, the major inhibitory neurotransmitter in the brain, are effective anxiolytics. These observations raise the possibility that transient perturbations in the activity of neural circuits during development might induce compensatory changes in inhibition that could persist into adulthood and contribute to changes in anxiety-related behavior. To test this hypothesis, we treated mice continuously during the major period of forebrain synaptogenesis (P14-28) with the GABA-A receptor positive modulator diazepam and assessed anxiety-related behavior in adulthood. Control experiments confirmed anxiolytic effects of the drug following one day of treatment and the development of tolerance following two weeks of treatment. When tested in adulthood, one month after the end of treatment, diazepam-treated mice exhibited significantly increased behavioral inhibition in the open-field, elevated-plus maze, and novel object behavioral paradigms. Levels of benzodiazepine binding sites in amygdala and frontal cortex were specifically decreased in diazepam-treated mice demonstrating that homeostatic adjustments in GABA function persist into adulthood. Our results show that increased GABAergic activity can affect the developmental programming of anxiety-related behavior.

Simultaneous assessment of autonomic function and anxiety-related behavior in BALB/c and C57BL/6 mice.

In humans, anxiety is accompanied by changes in autonomic nervous system function, including increased heart rate, body temperature, and blood pressure, and decreased heart rate variability. In rodents, anxiety is inferred by examining anxiety-related behavioral responses such as avoidance and freezing, and more infrequently by assessing autonomic responses to anxiogenic stimuli. However, few studies have simultaneously measured behavioral and autonomic responses to aversive stimuli in rodents and it remains unclear whether autonomic measures are reliable correlates of anxiety-related behavior in these animal models. Here we recorded for the first time heart rate and body temperature in freely moving BALB/c and C57BL/6 mice during exposure to an unfamiliar environment. Our data show that upon exposure to a novel open field, BALB/c mice showed increased anxiety-related behavior, reduced heart rate and higher heart rate variability (HRV) when compared with C57BL/6 mice. Regression analysis revealed a significant correlation between both heart rate and long-term HRV measures and locomotor activity and time spent in the center of the open field, but no correlation between body temperature and any behavioral variables. In the free exploration test, in which animals were allowed direct access to a novel environment from a familiar environment without experimenter handling, significant correlations were found only between heart rate and total locomotor activity, but not time spent in the unfamiliar chamber despite increased anxiety-related behavior in BALB/c mice. These findings demonstrate that increased anxiety-related behavior in BALB/c mice is not associated with specific changes in heart rate, HRV, or body temperature.

Progressive neurodegeneration and motor disabilities induced by chronic expression of IL-1beta in the substantia nigra.

The functional role of the long-lasting inflammation found in the substantia nigra (SN) of Parkinson's disease (PD) patients and animal models is unclear. Proinflammatory cytokines such as interleukin-1beta (IL-1beta) could be involved in mediating neuronal demise. However, it is unknown whether the chronic expression of cytokines such as IL-1beta in the SN can alter neuronal vitality. The aim of this study was to investigate the effects of the chronic expression of IL-1beta in the adult rat SN using a recombinant adenovirus expressing IL-1beta. The chronic expression of IL-1beta for 60 days induced dopaminergic cell death in the SN and unilateral akinesia starting only at 21 days post-injection. Microglial cell activation and inflammatory cell infiltrate were associated with dopaminergic cell death and motor disabilities. Astrocytic activation was delayed and associated with scar formation. The chronic expression of a single proinflammatory cytokine as IL-1beta in the SN elicited most of the characteristics of PD, including progressive dopaminergic cell death, akinesia and glial activation. Our data suggest that IL-1beta per se is able to mediate inflammatory-mediated toxic effects in the SN if its expression is sustained. This model will be helpful to identify possible therapeutic targets related to inflammation-derived neurodegeneration in the SN.